What if corn had never been developed (or evolved, depending on what you believe) from teosinte? Would this lead to the greater use of other staple crops, such as amaranthe and wild rice, by Amerindian civilisations?
Perhaps this would mean a retardation of the development of Central American civilisations, and would certainly mean differences to their culture. Perhaps their populations would spike due to later introduction of Andean crops. In North America, agriculture patterns are likely to be very different.
Today, there would be no vast use of corn and its byproducts, what other crop would be used in its place?